The present invention concerns a method and apparatus for tempering the temperature of a liquid in a fluid conducting system. More particularly, the invention relates to tempering the temperature of water supplied to a fixture from a water heater in a fluid conducting system.
Thermally controlled or thermostatic mixing valves are well known. Valves of this type receive both hot and cold fluid, typically water, and allow the fluids to mix to an intermediate temperature. The temperature is controlled using a thermally responsive control member, such as a thermostat, to assist in maintaining the fluid temperature according to an established setting.
One particular application of thermostatic mixing valves is in connection with emergency shower and eyewash systems. Toxic and hazardous chemicals are used in many environments, whether inside a factory building or outside at a remote construction site. The Occupational Safety and Health Act of 1970 was enacted to assure that workers would be provided with safe and healthful working conditions. Pursuant to this act, the Occupational Safety and Health Administration adopted regulations which require the availability of emergency eyewash and shower equipment for use as a form of first aid treatment. Emergency shower and eyewash systems have proliferated in a wide range of industries, including automotive, food processing, chemical processing, petroleum refining, steel production, pulp and paper, and waste water treatment. In each of these industries, workers may be exposed to chemicals that may cause serious tissue damage and destruction. These emergency shower and eyewash facilities are commonly associated with permanent structures and may be located inside or outside factory buildings with access to hot and cold water.
In emergency fixture systems such as eyewash and emergency shower systems, even ground water of a moderate temperature (such as in the range of 50 degrees to 60 degrees F., as is common) is often perceived to be too cold, possibly discouraging sufficient duration of use of the emergency equipment. In addition, in northern climates, the ground water itself is sometimes barely above freezing, commonly near 35 degrees F. Under these circumstances, an emergency shower and eyewash system relying solely upon ground water often provides water that would be too cold to be endured for a sufficient period of time, even by a victim of a chemical accident.
As a result, emergency shower and eyewash systems have been designed to provide tempered water by blending relatively hotter water with relatively colder water. A range of temperatures between 65 degrees F. to 95 degrees F. is comfortable to most persons. To provide tempered water within this range, most emergency fixture systems include a source of hot water, typically in the range of 140 degrees F. to 160 degrees F., that is mixed with ambient ground water.
Many outdoor or other remote worksites such as construction sites may have the same or similar hazards that are associated with indoor worksites. Such remote worksites typically do not have a ready supply of hot water. Thus, workers at such sites exposed to chemicals or other irritants typically do not have access to emergency fixture systems that provide an adequate supply of tempered fluid, properly directed, for a sufficient period of time. Such workers may be required to resort to a ground-temperature water supply from a garden hose, a squirt bottle eye rinse apparatus, or other less suitable sources of fluid to rinse the exposed area(s).
Emergency shower and eyewash systems must typically drench or rinse a user for at least 15 minutes. Thus, the source of tempered water should be able to provide the water for at least that length of time and to maintain the water within a comfortable temperature range for the user. In addition, the system should be able to maintain tempering of the water regardless of extreme fluctuations in the supply of hot or cold water to the thermostatic mixing valve. Often, a thermostatic mixing valve is used to maintain the water at an appropriately tempered temperature.
The valve should respond accordingly to failures in the supply of hot or cold water to the valve, as well as failure of the valve itself. The valve should respond to these failures without placing the user of the emergency shower or eyewash system in greater peril than the user would be without the emergency system. For example, if the cold water supply fails and only hot water in the range of 140 degrees F. to 160 degrees F. is supplied, the user could suffer burns that may be more serious than the exposure being treated. Thus, it is desirable for the valve to prevent or minimize exposure to such hot water.
In addition, fluid flow through a mixing valve must not be compromised due to relative differences in fluid pressure from a cold fluid supply and a hot fluid supply. If the relative pressure of one fluid supply is significantly higher than another fluid supply, a mixing valve may “bypass” the fluid supply of relatively lower pressure, allowing only fluid from the relatively higher pressure fluid supply to flow through a mixing valve. If a cold fluid supply is bypassed by a mixing valve, depending on the type of mixing valve used, the flow of hot fluid would either be fully restricted or would be moderately or significantly restricted. If the cold fluid is bypassed and the mixing valve fully restricts the flow of hot fluid, no fluid would flow. However, if the cold fluid is bypassed and the mixing valve only either moderately or significantly reduced the flow of hot fluid, a user could suffer severe burns. Conversely, if only cold fluid is supplied through a mixing valve, bypassing the hot fluid, a user may not be properly decontaminated by using an emergency shower and/or eyewash due to the fluid being too uncomfortably cold to the user. Accordingly, it is desirable for a system to include means as necessary to restrict the pressure of fluid from one or more fluid supply sources as to prevent unintended and undesirable bypass of a mixing valve.
Additionally, the flow of mixed fluid from an emergency fixture system with relatively low fluid flow requirements, such as an emergency eyewash system, and from an emergency fixture system with relatively high fluid flow requirements, such as an emergency shower system, must flow at appropriate temperatures. Accordingly, it is desirable, as necessary, to provide a system including one or more mixing valves allowing mixed fluid to flow to emergency fixture systems with relatively low and relatively high fluid flow requirements.
Thermostatic mixing valves typically include a housing including hot and cold inlets, a mixed fluid outlet, a valve control assembly to adjust the amounts of hot and/or cold fluid permitted to flow through the valve, and a thermostat to control movement of the control assembly. The thermostat is typically positioned at least partially in the housing to sense the temperature of the mixture of fluid therein. The thermostat includes a material that is responsive to changes in the fluid temperature. For example, if the temperature increases, then movement of the thermostat causes movement of the control assembly, either increasing the flow of cold fluid, decreasing the flow of hot fluid, or both.
Frequently, some fluid in the fluid circulation system of which the thermostatic mixing valve is a part has been stagnant for a period of time. During this stagnancy, the temperature of the hot fluid in the hot fluid supply line approaches ambient temperature, usually lower than the temperature of the hot fluid from the hot fluid supply. In a typical thermostatic mixing valve, when the temperature of the mixed fluid sensed by the thermostat is below the set point, the thermostat cooperates with the valve control assembly to increase the flow of hot fluid relative to the flow of cold fluid.
In such a stagnant fluid circulation system, when a fixture (such as an eyewash station) is eventually actuated, the thermostat is often exposed to mixed water at a temperature below the set point temperature, even if the ratio of water from the hot and cold fluid supplies otherwise would be proportioned (if the hot fluid were at temperature) to produce mixed fluid at the desired temperature. Accordingly, responsive changes in the thermostat cause the valve control assembly to move to a position that increases the flow of hot fluid relative to the flow of cold fluid, thus increasing the mixed fluid temperature. As the valve continues to receive the supply of fluid from the hot fluid supply line that was formerly stagnant, the thermostat continues to cause the valve control assembly to move to a position that further increases flow from the hot fluid supply line and/or decreases the flow of cold fluid. If a sufficient volume of stagnant fluid is in the supply line between the hot fluid supply and the mixing valve, this process may continue until the thermostat has caused the valve assembly to move to a position wide-open to maximize the flow of fluid from the hot fluid source.
Eventually, hot fluid from in the hot fluid supply (such as a water heater) progresses to the mixing valve. Because the valve control assembly is now wide-open to the hot fluid inlet, a large volume of hot fluid enters the valve housing through the hot fluid supply line that had previously been the source of the stagnant (and cooler) fluid. Once the hot fluid reaches the thermostat after mixing with whatever cold fluid is entering the valve, the thermostat responds to the temperature increase, causing the valve control assembly to move to reduce the flow of hot fluid and/or increase the flow of cold fluid. The length of time for the thermostat to respond as such and move the valve control assembly by a sufficient amount to reduce the temperature of mixed fluid below the set point can be long enough to permit a quantity of water above the set point temperature to flow from the valve.
Thus, in one aspect of the invention, a decontamination apparatus is provided, comprising a fluid supply inlet configured for coupling to a fluid supply source, a first fluid line coupled to the fluid supply inlet and formed to include a first passageway in which a first fluid flows, and a heat exchange assembly configured to heat the first fluid in the first fluid line. The apparatus also comprises a mixing valve including a valve body formed to include a first fluid inlet to receive the first fluid from the first fluid line, a second fluid inlet to receive a second fluid from a second fluid line, and a mixed fluid outlet. A decontamination fixture is coupled to the mixed fluid outlet configured to discharge the mixed fluid. Optionally, a support interconnects at least the heat exchange assembly, the first fluid line, the mixing valve, and the decontamination fixture to permit movement of the apparatus as a unit.
In an additional aspect of the invention, a restrictor may be positioned between a first fluid inlet and a mixing valve. In another aspect of the invention, one or more pressure reducing valves may be positioned within a first fluid line and/or a second fluid line prior to a mixing valve.
In yet another aspect of the invention, a first fluid from a first fluid line and a second fluid from a second fluid line may flow to a mixing valve and/or to a second mixing valve, allowing fluid to mix in a second mixing valve when fluid flow out of a decontamination apparatus is relatively low and allowing fluid to mix in a mixing valve and a second mixing valve when fluid flow out of a decontamination apparatus is relatively high. It is understood in this aspect of the invention that a first fluid from a first fluid line and a second fluid from a second fluid line may mix in one or both mixing valves under all conditions of fluid flow out of a decontamination apparatus.
In one illustrative example according to this aspect of the invention, the support is a frame including frame members coupled together, a platform coupled to the frame, and wheels coupled to the frame to facilitate movement of the decontamination apparatus.
In another illustrative example according to this aspect of the invention, the support includes a platform having a structure including a generally upwardly facing surface on which the heat exchange assembly, mixing valve, and decontamination fixture are supported, and a plurality of spaced apart support members coupled to and extending downwardly from the structure.
Illustratively according to this aspect of the invention, the first and second fluid lines comprise fluid provided by the fluid supply source.
Additionally illustratively according to this aspect of the invention the apparatus further comprises a junction in fluid communication with the fluid supply inlet, the junction splitting flow of fluid from the fluid supply source into the first fluid line and the second fluid line.
Illustratively according to this aspect of the invention the second fluid line configured to be coupled to a second fluid supply source and formed to include a second passageway in which a second fluid stream flows.
Illustratively according to this aspect of the invention the heat exchange assembly comprises a burner configured to combust fuel from a fuel source, and at least a portion of the first fluid passageway is proximate the burner so that when fuel from the fuel source is combusted at the burner, heat from the combustion is transferred into the first fluid in the first fluid passageway.
Additionally illustratively according to this aspect of the invention, the burner is coupled to a controller, the decontamination fixture includes an actuator to actuate a valve controlling flow of fluid from the decontamination fixture, the burner igniting upon actuation of the decontamination fixture by a signal sent by the controller.
Additionally illustratively according to this aspect of the invention the apparatus further comprises a fuel tank in which the fuel is stored, the fuel tank coupled to the frame to enable movement of the fuel tank upon movement of the frame.
Illustratively according to this aspect of the invention the apparatus further comprises wheels coupled to the frame to facilitate movement of the decontamination apparatus.
Additionally illustratively according to this aspect of the invention the apparatus further comprises a stand coupled to the frame to cooperate with the wheels to maintain decontamination apparatus in a position suitable for use by a user.
Illustratively according to this aspect of the invention, the apparatus further comprises a means for dampening temperature change of the first fluid prior to entry into the first fluid inlet of the thermostatic mixing valve so that the mixing valve can adjust to a particular temperature increase over a given time period.
Illustratively according to this aspect of the invention, the apparatus further comprises a diffuser coupled between the hot fluid line and the hot inlet to the mixing valve, the diffuser including a first fluid conduit and at least a second fluid conduit, a majority of the first fluid conduit being surrounded by the second fluid conduit, the first and second conduits being coupled together to cause fluid to flow into the first conduit, pass through a plurality of apertures formed in the first conduit, and into fluid outside the first conduit and in the second conduit.
Illustratively according to this aspect of the invention, the decontamination fixture is an eyewash fixture including a basin and at least one nozzle directed at least partially upwardly.
Illustratively according to this aspect of the invention, the decontamination fixture is a drench shower having fluid outlets directed at least partially downwardly.
Illustratively according to this aspect of the invention, the decontamination fixture is a wand including a trigger configured to be actuated by a user and a spray nozzle to direct the flow of fluid from the wand depending on a direction selected by a user.
According to another aspect of the invention, an apparatus for increasing the time period over which a temperature change occurs at a point in a fluid conducting system having fluid flowing therethrough comprises a first conduit having first and second ends and a plurality of openings provided between the first and second ends, a second conduit having first and second ends, the second conduit being coupled to the first conduit and at least partially surrounding at least a portion of the first conduit, wherein at least one of the openings is in the portion of the first conduit surrounded by the second conduit, one of the second conduit and the first conduit including a fluid inlet, and the other of the second conduit and the first conduit including a fluid outlet, wherein the first and second conduits are arranged to permit fluid to flow from the inlet to the outlet.
Illustratively according to this aspect of the invention, the second conduit and the first conduit are connected together to permit fluid to flow from the fluid inlet toward the fluid outlet.
Additionally illustratively according to this aspect of the invention, the first conduit and the second conduit are coupled together by a union that seals a first end of each of the first and second conduit so that fluid is inhibited from passing from the first end of the first conduit into the region between the first and second conduits adjacent the first end of the first conduit.
Further illustratively according to this aspect of the invention, a second end of the second conduit is sealed with a cap to prevent fluid from flowing out of the second end of the second conduit.
Further illustratively according to this aspect of the invention, a second end of the first conduit is spaced apart from the cap to permit fluid to flow from the second end of the first conduit adjacent the cap, and into the region between the first and second conduits.
Additionally illustratively according to this aspect of the invention, the union is formed to include an outlet to permit fluid to flow from the first end of the second conduit out of the outlet.
Further illustratively according to this aspect of the invention, the union includes a first end having an opening sized to receive the first end of the second conduit, and the union includes a second end having an opening sized to receive the first end of the first conduit.
Further illustratively according to this aspect of the invention, the first and second ends of the union are separated by a generally frustoconical reducing region.
Illustratively according to this aspect of the invention, the first and second fluid conduits are coupled so that fluid flowing within the first conduit flows substantially in the opposite direction as fluid flowing within the second conduit.
Additionally illustratively according to this aspect of the invention, the apparatus further comprises a third fluid conduit, wherein at least a portion of the first fluid conduit is surrounded by the second and third fluid conduits, and at least a portion of the second fluid conduit is surrounded by the third fluid conduit.
Further illustratively according to this aspect of the invention, the fluid flowing through and immediately adjacent to the first and third fluid conduits flows in a direction substantially parallel within each conduit.
Illustratively according to this aspect of the invention, the apparatus further comprises a plurality of apertures in the second fluid conduit comprise a first aperture, a second aperture, and a third aperture, the first aperture being spaced from the second aperture by a first distance, and the second aperture being spaced from the third aperture a second distance, the first distance being greater than the second.
Illustratively according to this aspect of the invention, the first and second fluid conduits define a void having a volume capable of receiving at least 0.13 gallons of fluid.
Additionally illustratively according to this aspect of the invention, the first, second and third conduits define a void having a volume capable of receiving at least 0.9 gallons of fluid.
Illustratively according to this aspect of the invention, the plurality of each of the apertures is substantially of one of the shapes selected from the group consisting of: circular, square, rectangular, diamond-shaped, ovular, triangular, and irregular.
According to another aspect of the invention, a fluid mixing apparatus for use in a fluid flow network comprises a mixing valve including a housing having a hot fluid inlet, a cold fluid inlet, a mixed fluid outlet, a mixing region, and a movable valve assembly to adjust the relative flow of fluid through the hot fluid inlet and the cold fluid inlet, and a first fluid conduit in fluid communication with the mixing valve, the first fluid conduit including an inlet through which fluid flows from a hot fluid supply line and an outlet through which fluid flows toward the mixing valve, the first fluid conduit constructed to expose fluid flowing through the inlet to a heat sink.
Illustratively according to this aspect of the invention, the heat sink is a second fluid mass downstream of a first fluid mass. Additionally illustratively according to this aspect of the invention, the apparatus further comprises a second fluid conduit coupled to the first fluid conduit, the first fluid conduit formed to include the inlet and formed to include a first conduit outlet through which fluid is capable of flowing out of the first fluid conduit and into the second fluid conduit. Further illustratively according to this aspect of the invention, the apparatus further comprises a third conduit between the first and second fluid conduits. Additionally illustratively according to this aspect of the invention, the first fluid conduit has a length, and is formed to include a plurality of openings, at least one of the plurality of openings positioned between the ends of the first fluid conduit. Additionally illustratively according to this aspect of the invention, a portion of the first fluid conduit is surrounded by the second fluid conduit. Additionally illustratively according to this aspect of the invention, at least one of the first and second fluid conduits includes a plurality of fins extending from a surface of said one of the first and second fluid conduits. Further illustratively according to this aspect of the invention, said one of the first and second fluid conduits is formed to include a plurality of apertures, at least one of said plurality of apertures positioned between the ends of the fluid conduit including fins.
Illustratively according to this aspect of the invention, the heat sink is a thermally conductive material having a mass per unit of linear length of net fluid flow greater than the average mass per unit of linear length of net fluid flow in the fluid flow network. Additionally illustratively according to this aspect of the invention, the heat sink comprises copper.
Illustratively according to this aspect of the invention, the heat sink surrounds the first conduit so that fluid flowing from the first fluid conduit subsequently flows through a passageway defined by the heat sink.
According to another aspect of the invention a decontamination apparatus comprising a fluid heater, a cold fluid supply line, a hot fluid supply line for supplying hot fluid from the fluid heater to a thermostatic mixing valve, the thermostatic mixing valve having a hot fluid inlet for receiving fluid from to the hot fluid supply line, a cold fluid inlet for receiving fluid from the cold fluid supply line, and a mixed fluid outlet for supplying fluid to a mixed fluid supply line through which one, the other, or both of the hot and cold fluids flow from the thermostatic mixing valve, an emergency fixture connected to the mixed fluid supply line for supplying fluid therefrom to a user and configured to deliver the mixed fluid at a flow rate and pattern to decontaminate effectively at least a portion of the user's body, and a diffuser coupled between the hot fluid supply line and the thermostatic mixing valve for increasing the time over which a temperature change is observed at the hot fluid inlet.
In another aspect of the invention a decontamination apparatus comprises a fluid supply inlet configured for coupling to a fluid supply source, a circulation network coupled to the fluid supply inlet and formed to include a first passageway in which a first fluid flows, a heater to heat the first fluid stream in the circulation network, a decontamination fixture connected to the circulation network to receive heated fluid from the heater, and a support interconnecting at least the heater, fluid circulation network, and the decontamination fixture to permit movement of the apparatus as a unit.
Illustratively according to this aspect of the invention, the apparatus further comprises a mixing valve comprising a valve body formed to include a first fluid inlet to receive a first fluid from a first fluid line, a second fluid inlet to receive a second fluid from a second fluid line, and a mixed fluid outlet. Additionally illustratively according to this aspect of the invention, the mixing valve further includes a valve assembly operably coupled to a thermostat to move the valve assembly to adjust the flow of at least one of the first and the second fluids to control the mixed fluid temperature.
Additionally illustratively according to this aspect of the invention, the support is a pallet into which the tines of a fork truck can be inserted to lift and move the apparatus as a unit. Additionally illustratively according to this aspect of the invention, the support is a frame having wheels coupled thereto so that a user can move the apparatus as a unit. Additionally illustratively according to this aspect of the invention, the decontamination fixture includes a valve operated by an actuator, and operation of the actuator causes fluid to flow from the circulation network through the mixing valve and through the decontamination fixture. Further illustratively according to this aspect of the invention, operation of the actuator causes the heater to ignite and heat the fluid flowing through the circulation network.
Additionally illustratively according to this aspect of the invention, the apparatus further comprises a diffuser positioned in the circulation network to receive fluid from the heater, the diffuser configured to increase the time over which a temperature increase is observed at the inlet of the fluid from the heater to the mixing valve.
Illustratively according to this aspect of the invention, the apparatus further comprises a fuel tank to store fuel usable by the heater to generate heat for heating the fluid in the circulation network. Additionally illustratively according to this aspect of the invention, the support is a frame having wheels coupled thereto so that a user can move the apparatus as a unit.
Additionally illustratively according to this aspect of the invention, the heater is configured to heat fluid on demand as the fluid flows through the circulation network.
Illustratively according to this aspect of the invention, the heater includes a storage tank and is configured to heat fluid and store the heated fluid in the storage tank.
Additional features of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of a preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.